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* [PATCH] nvme-rdma: handle nvme completion data length
@ 2020-10-22  8:38 zhenwei pi
  2020-10-22  9:55 ` Chao Leng
  0 siblings, 1 reply; 4+ messages in thread
From: zhenwei pi @ 2020-10-22  8:38 UTC (permalink / raw)
  To: kbusch, hch, sagi, axboe; +Cc: pizhenwei, linux-kernel, linux-nvme

Hit a kernel warning:
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 0 at lib/refcount.c:28

RIP: 0010:refcount_warn_saturate+0xd9/0xe0
Call Trace:
 <IRQ>
 nvme_rdma_recv_done+0xf3/0x280 [nvme_rdma]
 __ib_process_cq+0x76/0x150 [ib_core]
 ...

The reason is that a zero bytes message received from target, and the
host side continues to process without length checking, then the
previous CQE is processed twice.

Handle data length, ignore zero bytes message, and try to recovery for
corrupted CQE case.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
---
 drivers/nvme/host/rdma.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 9e378d0a0c01..9f5112040d43 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1767,6 +1767,17 @@ static void nvme_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
 		return;
 	}
 
+	if (unlikely(!wc->byte_len)) {
+		/* zero bytes message could be ignored */
+		return;
+	} else if (unlikely(wc->byte_len < len)) {
+		/* Corrupted completion, try to recovry */
+		dev_err(queue->ctrl->ctrl.device,
+			"Unexpected nvme completion length(%d)\n", wc->byte_len);
+		nvme_rdma_error_recovery(queue->ctrl);
+		return;
+	}
+
 	ib_dma_sync_single_for_cpu(ibdev, qe->dma, len, DMA_FROM_DEVICE);
 	/*
 	 * AEN requests are special as they don't time out and can
-- 
2.11.0


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http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] nvme-rdma: handle nvme completion data length
  2020-10-22  8:38 [PATCH] nvme-rdma: handle nvme completion data length zhenwei pi
@ 2020-10-22  9:55 ` Chao Leng
  2020-10-22 10:05   ` [External] " zhenwei pi
  0 siblings, 1 reply; 4+ messages in thread
From: Chao Leng @ 2020-10-22  9:55 UTC (permalink / raw)
  To: zhenwei pi, kbusch, hch, sagi, axboe; +Cc: linux-kernel, linux-nvme



On 2020/10/22 16:38, zhenwei pi wrote:
> Hit a kernel warning:
> refcount_t: underflow; use-after-free.
> WARNING: CPU: 0 PID: 0 at lib/refcount.c:28
> 
> RIP: 0010:refcount_warn_saturate+0xd9/0xe0
> Call Trace:
>   <IRQ>
>   nvme_rdma_recv_done+0xf3/0x280 [nvme_rdma]
>   __ib_process_cq+0x76/0x150 [ib_core]
>   ...
> 
> The reason is that a zero bytes message received from target, and the
> host side continues to process without length checking, then the
> previous CQE is processed twice.
> 
> Handle data length, ignore zero bytes message, and try to recovery for
> corrupted CQE case.
> 
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> ---
>   drivers/nvme/host/rdma.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index 9e378d0a0c01..9f5112040d43 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -1767,6 +1767,17 @@ static void nvme_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
>   		return;
>   	}
>   
> +	if (unlikely(!wc->byte_len)) {
> +		/* zero bytes message could be ignored */
> +		return;
> +	} else if (unlikely(wc->byte_len < len)) {
> +		/* Corrupted completion, try to recovry */
> +		dev_err(queue->ctrl->ctrl.device,
> +			"Unexpected nvme completion length(%d)\n", wc->byte_len);
> +		nvme_rdma_error_recovery(queue->ctrl);
> +		return;
> +	}
!wc->byte_len and wc->byte_len < len may be the same type of anomaly.
Why do different error handling?
In which scenario zero bytes message received from target? fault inject test or normal test/run?
> +
>   	ib_dma_sync_single_for_cpu(ibdev, qe->dma, len, DMA_FROM_DEVICE);
>   	/*
>   	 * AEN requests are special as they don't time out and can
> 

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Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [External] Re: [PATCH] nvme-rdma: handle nvme completion data length
  2020-10-22  9:55 ` Chao Leng
@ 2020-10-22 10:05   ` zhenwei pi
  2020-10-23  2:07     ` Chao Leng
  0 siblings, 1 reply; 4+ messages in thread
From: zhenwei pi @ 2020-10-22 10:05 UTC (permalink / raw)
  To: Chao Leng; +Cc: sagi, linux-kernel, linux-nvme, axboe, kbusch, Yibo Zhu, hch

On 10/22/20 5:55 PM, Chao Leng wrote:
> 
> 
> On 2020/10/22 16:38, zhenwei pi wrote:
>> Hit a kernel warning:
>> refcount_t: underflow; use-after-free.
>> WARNING: CPU: 0 PID: 0 at lib/refcount.c:28
>>
>> RIP: 0010:refcount_warn_saturate+0xd9/0xe0
>> Call Trace:
>>   <IRQ>
>>   nvme_rdma_recv_done+0xf3/0x280 [nvme_rdma]
>>   __ib_process_cq+0x76/0x150 [ib_core]
>>   ...
>>
>> The reason is that a zero bytes message received from target, and the
>> host side continues to process without length checking, then the
>> previous CQE is processed twice.
>>
>> Handle data length, ignore zero bytes message, and try to recovery for
>> corrupted CQE case.
>>
>> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
>> ---
>>   drivers/nvme/host/rdma.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
>> index 9e378d0a0c01..9f5112040d43 100644
>> --- a/drivers/nvme/host/rdma.c
>> +++ b/drivers/nvme/host/rdma.c
>> @@ -1767,6 +1767,17 @@ static void nvme_rdma_recv_done(struct ib_cq 
>> *cq, struct ib_wc *wc)
>>           return;
>>       }
>> +    if (unlikely(!wc->byte_len)) {
>> +        /* zero bytes message could be ignored */
>> +        return;
>> +    } else if (unlikely(wc->byte_len < len)) {
>> +        /* Corrupted completion, try to recovry */
>> +        dev_err(queue->ctrl->ctrl.device,
>> +            "Unexpected nvme completion length(%d)\n", wc->byte_len);
>> +        nvme_rdma_error_recovery(queue->ctrl);
>> +        return;
>> +    }
> !wc->byte_len and wc->byte_len < len may be the same type of anomaly.
> Why do different error handling?
> In which scenario zero bytes message received from target? fault inject 
> test or normal test/run?

Zero bytes message could be used as transport layer keep alive mechanism 
(I's also developing target side transport layer keep alive now. To 
reclaim resource, target side needs to close dead connections even kato 
is set as 0).

>> +
>>       ib_dma_sync_single_for_cpu(ibdev, qe->dma, len, DMA_FROM_DEVICE);
>>       /*
>>        * AEN requests are special as they don't time out and can
>>

-- 
zhenwei pi

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [External] Re: [PATCH] nvme-rdma: handle nvme completion data length
  2020-10-22 10:05   ` [External] " zhenwei pi
@ 2020-10-23  2:07     ` Chao Leng
  0 siblings, 0 replies; 4+ messages in thread
From: Chao Leng @ 2020-10-23  2:07 UTC (permalink / raw)
  To: zhenwei pi; +Cc: sagi, linux-kernel, linux-nvme, axboe, kbusch, Yibo Zhu, hch



On 2020/10/22 18:05, zhenwei pi wrote:
> On 10/22/20 5:55 PM, Chao Leng wrote:
>>
>>
>> On 2020/10/22 16:38, zhenwei pi wrote:
>>> Hit a kernel warning:
>>> refcount_t: underflow; use-after-free.
>>> WARNING: CPU: 0 PID: 0 at lib/refcount.c:28
>>>
>>> RIP: 0010:refcount_warn_saturate+0xd9/0xe0
>>> Call Trace:
>>>   <IRQ>
>>>   nvme_rdma_recv_done+0xf3/0x280 [nvme_rdma]
>>>   __ib_process_cq+0x76/0x150 [ib_core]
>>>   ...
>>>
>>> The reason is that a zero bytes message received from target, and the
>>> host side continues to process without length checking, then the
>>> previous CQE is processed twice.
>>>
>>> Handle data length, ignore zero bytes message, and try to recovery for
>>> corrupted CQE case.
>>>
>>> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
>>> ---
>>>   drivers/nvme/host/rdma.c | 11 +++++++++++
>>>   1 file changed, 11 insertions(+)
>>>
>>> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
>>> index 9e378d0a0c01..9f5112040d43 100644
>>> --- a/drivers/nvme/host/rdma.c
>>> +++ b/drivers/nvme/host/rdma.c
>>> @@ -1767,6 +1767,17 @@ static void nvme_rdma_recv_done(struct ib_cq *cq, struct ib_wc *wc)
>>>           return;
>>>       }
>>> +    if (unlikely(!wc->byte_len)) {
>>> +        /* zero bytes message could be ignored */
>>> +        return;
Resource leak, need nvme_rdma_post_recv.
>>> +    } else if (unlikely(wc->byte_len < len)) {
>>> +        /* Corrupted completion, try to recovry */
>>> +        dev_err(queue->ctrl->ctrl.device,
>>> +            "Unexpected nvme completion length(%d)\n", wc->byte_len);
>>> +        nvme_rdma_error_recovery(queue->ctrl);
>>> +        return;
>>> +    }
>> !wc->byte_len and wc->byte_len < len may be the same type of anomaly.
>> Why do different error handling?
>> In which scenario zero bytes message received from target? fault inject test or normal test/run?
> 
> Zero bytes message could be used as transport layer keep alive mechanism (I's also developing target side transport layer keep alive now. To reclaim resource, target side needs to close dead connections even kato is set as 0).
nvme over fabric protocol do not define this.
May be async event is a option for target keep alive(if kato set as 0).
> 
>>> +
>>>       ib_dma_sync_single_for_cpu(ibdev, qe->dma, len, DMA_FROM_DEVICE);
>>>       /*
>>>        * AEN requests are special as they don't time out and can
>>>
> 

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

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-- links below jump to the message on this page --
2020-10-22  8:38 [PATCH] nvme-rdma: handle nvme completion data length zhenwei pi
2020-10-22  9:55 ` Chao Leng
2020-10-22 10:05   ` [External] " zhenwei pi
2020-10-23  2:07     ` Chao Leng

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